§ 2. The Root.
18. Roots ordinarily produce neither buds, leaves, nor flowers. Their branches, called fibres when slender and long, proceed irregularly from any part of their surface.
19. Although roots proceed usually from the base of the stem or stock, they may also be produced from the base of any bud, especially if the bud lie along the ground, or is otherwise placed by nature or art in circumstances favourable for their development, or indeed occasionally from almost any part of the plant. They are then often distinguished as adventitious, but this term is by some appHed to all roots which are not in prolongation of the original radicle.
20. Roots are
fibrous, when they consist chiefly of slender fibres.
tuberous, when either the main root or its branches are thickened into one or more short fleshy or woody masses called tubers (25).
taproots, when the main root descends perpendicularly into the earth, emitting only very small fibrous branches.
22. The stock of a herbaceous perennial, or the lower part of the stem of an annual or perennial, or the lowest branches of a plant, are sometimes undergroimd and assume the appearance of a root. They then take the name of rhizome. The rhizome may always be distinguished from the true root by the presence or production of one or more buds, or leaves, or scales.